Effect of Spraying Power on Oxidation Resistance of MoSi2-ZrB2 Coating for Nb-Si Based Alloy Prepared by Atmospheric Plasma

Abstract

The MoSi2-ZrB2 coatings were prepared on Nb-Si based alloy by atmospheric plasma spraying with the spraying power 40, 43 and 45 kW. The effect of spraying power on the microstructure and oxidation resistance of MoSi2-ZrB2 coating at 1250 °C were studied. The results showed that the main constituent phases of coatings were MoSi2 at all spraying power. The coating became more compact as the spraying power increased. The coating prepared at 45 kW was dense and uniform, which exhibited the best oxidation resistance due to the formation of a dense and uniform glass layer consisting of SiO2 and ZrSiO4.

Effect of Al2O3 and SiO2 Inert-Fillers on the Microstructural Evolution and High Temperature Oxidation Resistance of B Modified Silicides Coatings Prepared by Pack Cementation Technology

“…The weight gains of the samples prepared with Al 2 O 3 and SiO 2 after oxidation at 1250 • C for 100 h were 2.77 mg cm −2 and 2.31 mg cm −2 , respectively. In our previous study [18], the Nb-Si bases alloy without coating experiences linear oxidation with a weight gain of 87.6 mg/cm 2 after oxidation at 1250 • C for 100 h, suggesting that the coatings showed good oxidation resistance protecting the substrate from oxidation. The oxidation mechanism of B modified coating conforms to the parabolic law (Figure 4b) according to Equation (1) [9]:…”

“…Consequently, deposition of coatings that can form dense, adherent and slow growing oxide scales is considered an effective way to address the requirement of the enhanced oxidation resistance and high-strength of Nb−Si based alloys [14,15]. Aluminide and silicide coatings, which can produce continuous Al 2 O 3 and SiO 2 scales at high temperature, have been widely studied [16][17][18]. In particular, silicide coatings are more attractive due to their higher application temperature.…”

Oxidation Behavior and Microstructural Evolution of ZrB2–35MoSi2–10Al Composite Coating

“…Zr-based oxides have high melting temperatures (ZrO 2 -2715 • C, ZrSiO 4 -2550 • C) and CTEs (ZrO 2 -10.5 × 10 −6 • C −1 , ZrSiO 4 -4.9 × 10 −6 • C −1 ) in contrast with pure SiO 2 (1650 • C and 0.55 × 10 −6 • C −1 ). Therefore, their dispersion in glass could increase the melting temperature and the CTE of silica, which could minimize the difference in CTE between silica and MoSi 2 , reducing the internal stress of the coating [52].…”

Metallothermic Reduction of MoO3 on Combustion Synthesis of Molybdenum Silicides/MgAl2O4 Composites

“…Molybdenum silicides, Mo 3 Si, Mo 5 Si 3 and MoSi 2 , are promising intermetallic materials for ultrahigh-temperature structural applications. Besides a high melting point over 2020 • C, they possess high strength, excellent oxidation resistance, corrosion resistance, creep resistance and good compatibility with ceramic reinforcements [1][2][3][4][5][6][7][8]. To improve the refractory property of transition metal silicides, magnesium aluminate spinel (MgAl 2 O 4 ) has been one of the potential additives, because of its unique combination of properties, including a high melting point (2135 • C), relatively low density, chemical inertness, high hardness, high mechanical strength and good thermal shock resistance [9][10][11][12].…”